Percolative conductivity in alkaline earth silicate melts and glasses

TL;DR

This paper investigates the percolative electrical conductivity in alkaline earth silicate glasses and melts, revealing a phase transition at a specific composition that influences ion mobility and overall conductivity.

Contribution

It demonstrates that the threshold behavior in conductivity is linked to a rigid-floppy elastic phase transition near a critical composition.

Findings

Conductivity increases linearly beyond the threshold composition.

The phase transition affects calcium ion mobility.

Elastic softening correlates with enhanced ion diffusion.

Abstract

Ion conducting $(CaO)_x(SiO_2)_{1-x}$ glasses and melts show a threshold behaviour in dc conductivity near $x=x_t=0.50$, with conductivities increasing linearly at $x>x_t$. We show that the behaviour can be traced to a rigid ($x<0.50$) to floppy ($x>0.50$) elastic phase transition near $x=x_t$. In the floppy phase, conductivity enhancement is traced to increased mobility or diffusion of $Ca^{2+}$ carriers as the modified network elastically softens.